Yes. From the 1 July 2014 ISAs became more flexible so not only can you transfer from a cash ISA into a stocks and shares ISA, but you can now also transfer money from your existing stocks and shares ISA into a cash ISA.
This change is important for those savers who have in the past used stocks and shares ISAs in an effort to receive improved returns, but no longer want to risk their capital investment and so would like to switch to a cash ISA.
When transferring an ISA you should always make sure you do it through an ISA transfer request with your bank or building society, otherwise your account will lose its tax-free status, which applies now and in the future.